Silencing device for internal-combustion engines, particularly applicable for use on aircraft



R. BLACKBURN. SILENCING DEVICE FOR INTERNAL COMBUSTION ENGINES, PARTICULARLY APPLICABLE FOR USE ON AIRCRAFT.

APPLICATION FILED APR.26, I920.

Patented Mar. 29, 1921.

2 SHEETSSHEET l- R. BLACKBURN. SILENCING DEVICE FOR INTERNAL COMBUSTION ENGINES, PARTICU 0N AIRCRAFT.

APPLICATION FILED APII.26. I920. 1,37 3,221. Patented Mar. 29, 1921.

2 SHEETSSHEEI 2.

LARLY APPLICABLE FORUSE UNITED STATES PATENT QFFICE.

QBGSBERT BLACKBURN, OF BOSTDN SPA, ENGLAND, ASSIGNOR TO JOHN REED, OF

' CORBRIDGE-ON-TYNE, ENG-LAND.

CABLE FDR USE ON AIRCRAFT.

Specification of Letters Patent.

Patented Mar. 29, 1921.

Application filed April 26, 1920. Serial No. 376,592.

aircraft, and the object of the present invention is to provide an improved construction of silencing device by which the sound of the explosions of the engine, to which the silencing device is connected, shall be rendered practically inaudible; that thedevice, hereafter termed a silencer, shall pro duce the least possible back pressure, while at no time shall the products of combustion leaving the silencer be visible, which latter is a feature particularly important in aircraft, and especially in aircraft employed for the purposes of war.

To attain these objects and according to this invention, there is provided a closed conical casing, of a suitable length, and within this said conical casing there is a tube one open end of which is adjacent to the closed narrow end of the conical casing, while the opposite end of the tube extends through the opposite andwider end of the conical casing and is also open.

A pipe or pipes conveying the products of combustion from the engine or engines is or are connected to the wider end of the conical casing and opens or open into the annular chamber formed therein, the pipes being so tangentially directed and connected to the said casing thatthe explosion gases will revolve or spin around the exterior of the tube within the annular chamber formed between the tube and the said casing. v

The wall of the before mentioned tube is formed with series of apertures which increase in area as they increase in distance from the point or points of delivery of the gases to the annular chamber, so that as the spinning gases travel through the length of the annular chamber they will pass through the apertures into the tube and also through the open end of the latter within the chamber and be delivered through the open end of the tube exterior of the chamber.

According to the present invention the casing is slightly conical, the pipes conveying the exhaust gases being connected in a tangential mannerat the larger end. As the gases enter the casing, they are spun around the annular chamber and some will escape through the apertures in the central tube, but the main portion will whirl completely down the length of the casing and pass in at the end of the control tube and then back through the tube whence they are ejected into the atmosphere. By this means a much greater length of travel will be given to the gases for expansion and slowing up purposes by passing them first down the annular chamber with a revolving movement and then back again through the central tube, and there will be less liability to increase back pressure than if the gases were made to filter slowly through the apertures in the central pipe to the outlet.

The invention will be further described with reference to the accompanyin drawings, Figure 1 of which shows in si e elevation and Fig. 2 is plan view, a silencer constructed according to this invention. Fig. 3 is a longitudinal section of the silencer, and Fig. 4 a cross section taken upon the line X Y of Fig. 3.

A conical closed casing 1 of circular cross section is secured by any suitable means, suchfor instance as the straps 2, to the frame of the aircraft or other machine upon which the internal combustion engine, with which the silencer is to be used, is attached.

Within the closed casing 1 and central therewith is a tube 3, one endbeing open and terminating adjacent to the smaller closed end 4 of the casing 1, while the other end of the tube 3 passes through the larger end and projects beyond.

Pipes 5 connected with the casing 1 at its larger end are provided for conveying the products of combustion or waste gases from the engine cylinders to the silencer. These pipes are connected to the casing l, at its larger end, in such a manner that the gases passing therethrough enter the annular chamber formed between the casing 3. and

the tube 3, tangentially (see Fig. l), Whereby a spinning motion of the gases Will be set up around the tube 3.

In the wall of the tube 3 are formed annular series of circular holes 6 increasing in area from the point where the gases enter the casing to the end of the tube-adjacent I to the part 4.

The waste gases from the engine or engines pass through the pipes 55 enter the casing 1, and pass with a spinning motion throughout the length ofthe annular chamber. During such passage a portion of the gases will pass through the holes 6 and the remainder will enter the open end of the tube 3 within the casing 1, the whole being delivered through the opposite open end of the tube 3 exterior of the casing.

What I claim as my invention and desire to secure by Letters Patent is 1. lln silencing devices for internal combustion engines; the combination of a closed conical casing, an open-ended tube entering said casing at its larger end, extending axially therein and terminating within and adjacent to the smaller end of said conical casing to constitute an open exit tube from said casing, said exit tube within said casing having series of apertures through its Wall,'

said apertures increasing in area as they increase in distance from the larger end of said casing, a pipe connected at one end tangentially to and communicating with the interior of said casing at its larger end to convey and deliver the exhaust gases from the engine tangentially to the annular space within said casing to cause said gases to spin toward the'smaller end of said conical casing and to escape through said apertures of said 'exit tube and through the inner open end of said exit tube to the atmosphere.

2. In silencing devices for internal combustion engines; the combination of a closed conical casing, an open-ended tube entering said casing at its larger end, extending axially therein and terminating within and adjacent. to the smaller end of said conical casing to constitute an open exit tube from said casing, said exit tube within said casing having series of apertures through its wall, said apertures increasing in area as they increase in distance from the larger end of said casing, a plurality of pipes connected at one end tangentially to and communicating with the interior of said casing at its larger end to convey and deliver the exhaust gases from the engine tangentially to the annular space within said casing to cause said gases to spin toward the smaller end of said conical casing and to escape through said apertures of said exit tube and through the inner open end of said exit tube to the atmosphere.

In Witness whereof I have hereunto set my hand in the presence of two witnesses.

R. BLACKBURN.

Vitnesses: V

W NIFRED M. CLAYTON, P. GAssETr. 

